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Abstract: We explore the defect formation on single‐layer graphene partially suspended over a microcavity upon etching by a focused electron beam in a reactive oxygen atmosphere. The formation of oxygenated defects in an area of several μm2 around the cut is studied by Raman spectroscopy. The narrow symmetric Raman D band has the same bandwidth as the G band line width of supported graphene. For suspended graphene, the D bandwidth is larger. From the ratio of the intensity of the Raman D and D′ band (ID/ID′), it is concluded that mainly sp3‐type defects are formed on supported graphene and more defects with a different spectral signature are formed on suspended graphene. Annealing in reductive H2/Ar atmosphere is found to remove bonded oxygen on supported graphene, whereas on suspended graphene with higher density of defects, defects are removed only partially. [ABSTRACT FROM AUTHOR]

Sub‐micrometric and ultrathin gold cavities sustain several high order planar plasmon resonances in the visible to near‐infrared spectral window that open new perspectives for the realization of self‐assembled metasurfaces or integrated components for nano‐optics. This article investigates in detail the far‐field spectral features of these multimodal crystalline gold nanoprisms, deposited on either dielectric (glass) or metallic substrates (Au, Al) by dark‐field scattering spectroscopy. Relying on the computation of the plasmonic density of states, the signature of each planar resonance is de‐convoluted from the experimental global response of single cavities as a function of the cavity size and the substrate nature. The redshifting dispersion of each resonance is extracted from this decomposition analysis and agrees with predictions from a Green dyadic method based numerical tool. In addition, in the presence of a metallic film, a characteristic redshift or blueshift of the global response is observed for each cavity that results from a metal‐specific redistribution of the resonances. The fine spectral tuning of high order plasmonic resonances achieved here reveals the potential of the metal–insulator–metal gap geometry for a static modal engineering within ultrathin gold cavities. [ABSTRACT FROM AUTHOR]